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Abstract:

A method and apparatus for detecting location information using a
navigation algorithm are provided. The method includes searching for
neighboring Global Positioning System (GPS) satellites, receiving, if at
least one GPS satellite is detected, pseudo-range information from at
least one of the detected GPS satellites and storing the received
pseudo-range information, calculating a displacement of a pedestrian
terminal based on step detection of a pedestrian, correcting the
calculated displacement of the pedestrian terminal using the received
pseudo-range information, and measuring the location of the pedestrian
terminal is measured using the corrected displacement.

Claims:

1. A method for measuring a location of a pedestrian terminal, the method
comprising: searching for neighboring Global Positioning System (GPS)
satellites; receiving, if at least one GPS satellite is detected,
pseudo-range information from at least one of the detected GPS satellites
and storing the received pseudo-range information; calculating a
displacement of a pedestrian terminal based on a detected number of steps
taken by a pedestrian; correcting the calculated displacement of the
pedestrian terminal using the received pseudo-range information; and
measuring the location of the pedestrian terminal using the corrected
displacement.

2. The method of claim 1, wherein the displacement calculation comprises
calculating the displacement of the pedestrian terminal by a Pedestrian
Dead Reckoning (PDR) algorithm that estimates a location of a pedestrian
terminal according to gait characteristics of the pedestrian.

3. The method of claim 2, wherein the displacement correction comprises:
confirming the displacement of the pedestrian terminal by a pedestrian
navigation system; calculating a distance between the pedestrian terminal
and the at least one GPS satellite using the calculated displacement of
the pedestrian terminal and orbit information about the at least one GPS
satellite; and correcting the displacement of the pedestrian terminal
using a difference between the received pseudo-range information and the
calculated distance between the pedestrian terminal and the at least one
GPS satellite.

4. The method of claim 1, wherein the reception and storing of
pseudo-range information comprises receiving the pseudo-range information
from the at least one of the detected GPS satellites, detecting and
correcting an error of the received pseudo-range information using a
filter, and storing the corrected pseudo-range information.

5. An apparatus for measuring a location of a pedestrian terminal, the
apparatus comprising: a user interface for interfacing with a user; a
Global Positioning System (GPS) receiver for searching for neighboring
GPS satellites and for receiving, if at least one GPS satellite is
detected, pseudo-range information from at least one of the detected GPS
satellites; and a controller for calculating a displacement of a
pedestrian terminal based on a detected number of steps taken by a
pedestrian, for correcting the calculated displacement of the pedestrian
using the received pseudo-range information, and for measuring the
location of the pedestrian terminal using the corrected displacement.

6. The apparatus of claim 5, wherein the controller calculates the
displacement of the pedestrian terminal by a Pedestrian Dead Reckoning
(PDR) algorithm that estimates a location of a pedestrian according to
gait characteristics of the pedestrian.

7. The apparatus of claim 6, wherein the controller confirms the
displacement of the pedestrian terminal by a pedestrian navigation
system, calculates a distance between the pedestrian terminal and the at
least one GPS satellite using the calculated displacement of the
pedestrian terminal and orbit information about the at least one GPS
satellite, and corrects the displacement of the pedestrian terminal using
a difference between the received pseudo-range information and the
calculated distance between the pedestrian terminal and the at least one
GPS satellite.

8. The apparatus of claim 5, further comprising a filter unit for
detecting and correcting an error of the received pseudo-range
information.

9. The apparatus of claim 5, wherein the controller controls selective
coupling of two navigation algorithms or use of only one of the two
navigation algorithms according to the number of GPS signals received
through the GPS receiver.

10. The apparatus of claim 5, further comprising an accelerometer for
measuring an acceleration of the apparatus according to a motion of the
apparatus.

11. The apparatus of claim 5, wherein the controller comprises: a
satellite navigation algorithm executor for receiving information about a
location of a user from a visible satellite and providing information
about the location of the user; and a PDR algorithm executor for
estimating a location of a user according to gait characteristics of the
user.

12. The apparatus of claim 5, wherein if the number of GPS signals
received through the GPS receiver is 4 or larger, the controller uses a
loosely coupled scheme in which a location and velocity of the GPS
receiver are used as measurements for a coupled system.

13. The apparatus of claim 5, wherein if the number of GPS signals
received through the GPS receiver is 3 or smaller, the controller
compares strengths of the GPS signals with a threshold, and if the
strengths of the GPS signals are higher than the threshold, the
controller uses a tightly coupled scheme in which pseudo-range
information and pseudo-range change rate information received through the
GPS receiver are used as measurements.

14. The apparatus of claim 6, wherein if no GPS signal is received
through the GPS receiver, the controller detects location information
about the user using one of two navigation algorithms, the one of the
navigation algorithms being the PDR algorithm.

17. At least one non-transitory processor readable medium for storing a
computer program of instructions configured to be readable by at least
one processor for instructing the at least one processor to execute a
computer process for performing the method as recited in claim 1.

Description:

PRIORITY

[0001] This application is a National Stage application under 35 U.S.C.
§371 of an International application filed on Jan. 4, 2012 and
assigned application No. PCT/KR2012/000065, and claims the benefit under
35 U.S.C. §365(b) of a Korean patent application filed on Jan. 7,
2011 in the Korean Intellectual Property Office and assigned Serial No.
10-2011-0001990, the entire disclosure of which is hereby incorporated by
reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to detection of location information
about a user. More particularly, the present invention relates to an
apparatus and method for detecting location information about a user
using a radio navigation system and a pedestrian navigation system.

[0004] 2. Description of the Related Art

[0005] Personal navigation systems have been designed to provide
person-centered route guidance. Such systems locate a pedestrian to be
route-guided and guide the pedestrian to a route based on his or her
location. Personal navigation systems can be classified into a satellite
navigation system, an inertial navigation system, a pedestrian navigation
system, and the like, according to movement types.

[0006] A satellite navigation system can provide information about a
current location and a route to a desired destination to a user using
satellites. An example of a satellite navigation system is a car
navigation system.

[0007] A car navigation system locates a vehicle, provides the vehicle's
driver with an optimum route, and guides the driver along the optimum
route. In general, a car navigation system calculates the current
location of the vehicle using a Global Positioning System (GPS) sensor
and provides route guidance from the current location to a destination.

[0008] An inertial navigation system calculates the acceleration of a user
by means of an accelerometer such as a gyroscope sensor, calculates the
current velocity of the user based on the acceleration, and detects the
current location of the user based on the velocity. The inertial
navigation system is applied mainly to a submarine, an aircraft, a
missile, etc. Recently, route guidance has been provided to vehicles or
aircrafts using a composite navigation system having an accelerometer in
addition to the satellite navigation system.

[0009] A pedestrian navigation system provides pedestrian-centered route
guidance; not car-centered route guidance. Although the pedestrian
navigation system is similar to the car navigation system, the former
measures the location of a route-guidance object more accurately and
provides more detailed route guidance than the latter because the
route-guidance object is a pedestrian, which is slower than a car.

[0010] Accordingly, the car navigation system and the pedestrian
navigation system provide route guidance using different algorithms. For
example, the navigation system locates a car using a Global Positioning
System (GPS) sensor, whereas the pedestrian navigation system locates a
pedestrian by detecting the pedestrian's steps and strides. Therefore,
these two navigation systems should each have dedicated navigation
devices for performing their own algorithms.

[0011] However, in a case where both a car navigation device and a
pedestrian navigation device are necessary, a user must purchase both
navigation devices, resulting in increased cost and less portability. In
this context, a composite navigation device has recently been developed
to enable the car navigation system and the pedestrian navigation system
to be used together.

[0012] A shortcoming with the composite navigation device is that a user
should manually switch an operation mode between the car navigation
system and the pedestrian navigation system. That is, to use the
pedestrian navigation system while using the car navigation system, the
user must end the car navigation system manually and then activate the
pedestrian navigation system, or vice versa.

[0013] Therefore, navigation devices of the related art inconveniently
require a user to manually select the car navigation system or the
pedestrian navigation system. Moreover, if the user selects a wrong
navigation system by mistake, incorrect route guidance may be provided to
the user.

[0014] The above information is presented as background information only
to assist with an understanding of the present disclosure. No
determination has been made, and no assertion is made, as to whether any
of the above might be applicable as prior art with regard to the present
invention.

SUMMARY OF THE INVENTION

[0015] Aspects of the present invention are to address at least the above
mentioned problems and/or disadvantages and to provide at least the
advantages described below. Accordingly, an aspect of the present
invention is to provide an apparatus and method for detecting the
location of a user, automatically using car navigation or pedestrian
navigation selectively or both the car navigation and pedestrian
navigation in combination without user manipulation in a composite
navigation device that provides a car navigation system and a pedestrian
navigation system.

[0016] In accordance with an aspect of the present invention, a method for
measuring a location of a pedestrian terminal is provided. The method
includes searching for neighboring Global Positioning System (GPS)
satellites, receiving, if at least one GPS satellite is detected,
pseudo-range information from at least one of the detected GPS satellites
and storing the received pseudo-range information, calculating a
displacement of a pedestrian terminal based on a detected number of steps
taken by a pedestrian, correcting the calculated displacement of the
pedestrian using the received pseudo-range information, and measuring the
location of the pedestrian terminal using the corrected displacement.

[0017] In accordance with another aspect of the present invention, the
displacement calculation includes calculating the displacement of the
pedestrian terminal by a Pedestrian Dead Reckoning (PDR) algorithm that
estimates a location of a pedestrian terminal according to gait
characteristics of the pedestrian.

[0018] In accordance with another aspect of the present invention, the
displacement correction includes confirming the displacement of the
pedestrian terminal by a pedestrian navigation system, calculating the
distance between the pedestrian terminal and the at least one GPS
satellite using the calculated displacement of the pedestrian terminal
and orbit information about the at least one GPS satellite, and
correcting the displacement of the pedestrian terminal using a difference
between the received pseudo-range information and the calculated distance
between the pedestrian terminal and the at least one GPS satellite.

[0019] In accordance with another aspect of the present invention, the
reception and storing of pseudo-range information includes receiving the
pseudo-range information from the at least one of the detected GPS
satellites, detecting and correcting an error of the received
pseudo-range information using a filter, and storing the corrected
pseudo-range information

[0020] In accordance with another aspect of the present invention, an
apparatus for measuring a location of a pedestrian terminal is provided
The apparatus includes a user interface for interfacing with a user, a
GPS receiver for searching for neighboring GPS satellites and for
receiving, if at least one GPS satellite is detected, pseudo-range
information from at least one of the detected GPS satellites, and a
controller for calculating a displacement of a pedestrian terminal based
on a detected number of steps taken by a pedestrian, for correcting the
calculated displacement of the pedestrian terminal using the received
pseudo-range information, and for measuring the location of the
pedestrian terminal using the corrected displacement.

[0021] In accordance with another aspect of the present invention, the
controller calculates the displacement of the pedestrian terminal by a
PDR algorithm that estimates a location of a pedestrian terminal
according to gait characteristics of the pedestrian.

[0022] In accordance with another aspect of the present invention, the
controller confirms the displacement of the pedestrian terminal by a
pedestrian navigation system, calculates a distance between the
pedestrian terminal and the at least one GPS satellite using the
calculated displacement of the pedestrian terminal and orbit information
about the at least one GPS satellite, and corrects the displacement of
the pedestrian using a difference between the received pseudo-range
information and the calculated distance between the pedestrian terminal
and the at least one GPS satellite.

[0023] In accordance with another aspect of the present invention, the
apparatus further includes a filter unit for detecting and correcting an
error of the received pseudo-range information.

[0024] In accordance with another aspect of the present invention, the
controller controls selective coupling of two navigation algorithms or
uses only one of the two navigation algorithms according to the number of
GPS signals received through the GPS receiver.

[0025] In accordance with another aspect of the present invention, the
apparatus may further include an accelerometer for measuring an
acceleration of the apparatus according to a motion of the apparatus.

[0026] In accordance with another aspect of the present invention, the
controller may include a satellite navigation algorithm executor for
receiving information about a location of a user from a visible satellite
and providing information about the location of the user, and a PDR
algorithm executor for estimating a location of a user according to gait
characteristics of the user.

[0027] In accordance with another aspect of the present invention, if the
number of GPS signals received through the GPS receiver is 4 or larger,
the controller uses a loosely coupled scheme in which a location and
velocity of the GPS receiver are used as measurements for a coupled
system.

[0028] In accordance with another aspect of the present invention, if the
number of GPS signals received through the GPS receiver is 3 or smaller,
the controller compares strengths of the GPS signals with a threshold,
and if the strengths of the GPS signals are higher than the threshold,
the controller uses a tightly coupled scheme in which pseudo-range
information and pseudo-range change rate information received through the
GPS receiver are used as measurements.

[0029] In accordance with another aspect of the present invention, if no
GPS signal is received through the GPS receiver, the controller detects
location information about the user using one of two navigation
algorithms, one of the two navigation algorithms being the PDR algorithm.

[0030] In accordance with another aspect of the present invention, at
least one non-transitory processor readable medium is provided for
storing a computer program of instructions configured to be readable by
at least one processor for instructing the at least one processor to
execute a computer process for performing the methods herein.

[0031] As is apparent from the above description of the present invention,
in a composite navigation device that provides a satellite navigation
system and a PDR system, a car navigation system and a pedestrian
navigation system are automatically used selectively or in combination,
without a user's manipulation. Therefore, accurate location information
about a user can be provided in an environment where the car navigation
system cannot provide the location information about the user.

[0032] Other aspects, advantages, and salient features of the invention
will become apparent to those skilled in the art from the following
detailed description, which, taken in conjunction with the annexed
drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and other objects, features, and advantages of certain
exemplary embodiments of the present invention will be more apparent from
the following description taken in conjunction with the accompanying
drawings, in which:

[0034] FIG. 1 is a block diagram of a navigation device according to an
exemplary embodiment of the present invention;

[0035] FIG. 2 is a flowchart illustrating an operation for notifying the
location of a user using the navigation device according to an exemplary
embodiment of the present invention;

[0036]FIG. 3 is a flowchart illustrating an error correction operation
according to an exemplary embodiment of the present invention; and

[0037] FIGS. 4A to 5B are graphs illustrating filter tuning results
obtained by taking into account gait characteristics according to
exemplary embodiments of the present invention.

[0038] Throughout the drawings, it should be noted that like reference
numbers are used to depict the same or similar elements, features and
structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0039] The following description with reference to the accompanying
drawings is provided to assist in a comprehensive understanding of
exemplary embodiments of the invention as defined by the claims and their
equivalents. It includes various specific details to assist in that
understanding but these are to be regarded as merely exemplary.
Accordingly, those of ordinary skill in the art will recognize that
various changes and modifications of the embodiments described herein can
be made without departing from the scope and spirit of the invention. In
addition, descriptions of well-known functions and constructions may be
omitted for clarity and conciseness.

[0040] The terms and words used in the following description and claims
are not limited to the bibliographical meanings, but, are merely used by
the inventor to enable a clear and consistent understanding of the
invention. Accordingly, it should be apparent to those skilled in the art
that the following description of exemplary embodiments of the present
invention is provided for illustration purpose only and not for the
purpose of limiting the invention as defined by the appended claims and
their equivalents.

[0041] It is to be understood that the singular forms "a," "an," and "the"
include plural referents unless the context clearly dictates otherwise.
Thus, for example, reference to "a component surface" includes reference
to one or more of such surfaces.

[0042] Exemplary embodiments of the present invention use a Pedestrian
Dead Reckoning (PDR) system. The PDR system estimates the location of a
user based on the gait characteristics of the user. Because a general
integrated navigation system model is not viable, it is essential to
derive a model specialized for the PDR. Exemplary embodiments of the
present invention provide a method for coupling the PDR system with a
satellite navigation system using the features of the PDR system,
examples of such features being step detection, stride length estimation,
and heading estimation regarding a pedestrian.

[0043] According to exemplary embodiments of the present invention, the
two navigation systems (i.e., the PDR system and the satellite navigation
system) can be loosely coupled or tightly coupled. Depending on the
reception state of a Global Positioning System (GPS) signal, the two
systems may be coupled in a different manner. A composite navigation
system with the two systems coupled within it should consider information
output from each system on the same coordinate system.

[0044] That is, the PDR system may provide a location on a local
horizontal coordinate system, whereas the satellite navigation system may
provide a location on an Earth-Centered Earth-Fixed (ECEF) coordinate
system. Therefore, the two different coordinate systems may be converted
using an appropriate coordinate conversion matrix.

[0045] An exemplary embodiment of a navigation device that selectively
couples the two systems may have the following configuration.

[0046] FIG. 1 is a block diagram of a navigation device according to an
exemplary embodiment of the present invention.

[0047] Referring to FIG. 1, the navigation device includes a user
interface 101, a GPS receiver 103, an accelerometer 105, a navigation
algorithm controller 107, and a filter unit 113. The navigation algorithm
controller 107 includes a satellite navigation algorithm 109 and a PDR
algorithm 111.

[0048] Referring to FIG. 1, the user interface 101 may be configured with
an input device such as a keypad, a touch panel, or the like for
interfacing with a user. For instance, the user interface 101 may receive
a request for executing a navigation program from the user and may
provide the request to the navigation algorithm controller 107.

[0049] The GPS receiver 103 receives a GPS signal from a GPS satellite and
transmits the received GPS signal to the navigation algorithm controller
107. The GPS receiver 103 may receive one or more GPS signals which may
include position information and time information. In addition, the GPS
receiver 103 may receive information about a pseudo-range from at least
one satellite. The accelerometer 105 may be a 3-axis accelerometer and
may measure an acceleration according to a motion of the navigation
device. The accelerometer 105 may measure the acceleration of the
navigation device according to the motion of the navigation device using
an acceleration sensor.

[0050] The filter unit 113 may detect an error in an acceleration of the
navigation device based on a motion of the navigation device measured by
a specific filter and an error between a measured current location of the
navigation device and a destination, and may correct the error. That is,
when an actual location and an estimated location are different, the
error between the actual and an estimated location may be detected and
corrected so that the estimated location is as accurate to the actual
location as possible. In an exemplary embodiment of the present
invention, a Kalman filter may be used.

[0051] The navigation algorithm controller 107 may include the satellite
navigation algorithm 109 and the PDR algorithm 111 and may control
selective coupling of the two algorithms 109 and 111, or may use only one
of the two algorithms 109 and 111 by counting the number of GPS signals
received from the GPS receiver 103. For example, when four or more GPS
signals are received, the satellite navigation algorithm 109 and the PDR
algorithm 111 may be coupled loosely in such a manner that the satellite
navigation algorithm 109 is a main algorithm, and the PDR algorithm 111
is an auxiliary algorithm.

[0052] In exemplary embodiments, a loosely coupled scheme may be used in
most cases. Such a system may use the location and velocity of a GPS
receiver for measurement. Despite the advantage of having a simple
configuration, a loosely coupled scheme can provide information about a
user's location only if the number of visible satellites is 4 or larger.

[0053] In another example, if three or fewer GPS signals are received, the
navigation algorithm controller 107 may estimate a location and heading
by tightly coupling the satellite navigation algorithm 109 with the PDR
algorithm 111 such that information about a current location, a velocity,
and a heading of a user using the navigation device, as obtained by the
PDR algorithm 111, may be used together with satellite information
received through the GPS receiver 103.

[0054] According to exemplary embodiments of a tightly coupled scheme,
neighboring GPS satellites may be detected through the GPS receiver 103.
Pseudo-range information may be received from at least one of the
detected GPS satellites, the received pseudo-range information may be
stored, a displacement of a pedestrian (a displacement of a pedestrian
terminal) may be calculated using step detection of the pedestrian and
corrected using the received pseudo-range information, and the location
of the pedestrian 1 may be measured using a corrected value.

[0055] In exemplary embodiments, the displacement of the pedestrian may be
calculated by the PDR algorithm that estimates the location of a
pedestrian using the gait characteristics of the pedestrian.

[0056] In exemplary embodiments, the displacement of the pedestrian may be
corrected by calculating the distance between the pedestrian terminal and
a GPS satellite from which the pseudo-range information has been
received, using a calculated displacement of the pedestrian and using
orbit information related to the GPS satellite, and calculating the
difference between the distance between the pedestrian terminal and a GPS
satellite and the received pseudo-range information.

[0057] In exemplary embodiments, the tightly coupled scheme may use
pseudo-range information received at the GPS receiver 103 and may use
pseudo-range change rate information for measurements. As long as one or
more visible satellites exist, the tightly coupled scheme can provide
location information about a user.

[0058] An operation for providing location information about a user in the
navigation device having the above-described configuration will be
described below.

[0059] FIG. 2 is a flowchart illustrating an operation for notifying the
location of a user using the navigation device according to an exemplary
embodiment of the present invention.

[0060] Referring to FIG. 2, the navigation device receives a GPS signal
from the GPS receiver 103 in step 201. If the navigation device is
located in a poor reception area, it may not receive any GPS signal. On
the other hand, if the navigation device is located in an area with good
GPS reception, it may receive a plurality of GPS signals.

[0061] In step 203, the navigation device determines whether the number of
GPS signals received through the GPS receiver 103 is 4 or larger because
the satellite navigation algorithm 109 may be coupled with the PDR
algorithm 111 in a different manner according to the number of received
GPS signals.

[0062] If the number of GPS signals received through the GPS receiver 103
is 4 or larger, the navigation device determines that it is currently
located in an area where GPS signals are actively received and goes to
step 205. In step 205, the navigation device loosely couples the
satellite navigation algorithm 109 with the PDR algorithm 111 and
receives information about a current location and travelling route of the
navigation device according to the loosely coupled scheme.

[0063] On the other hand, if the number of GPS signals received through
the GPS receiver 103 is 3 or smaller, the navigation device determines
that it is currently located in a poor reception area where GPS signals
cannot be actively received and goes to step 207. In step 207, the
navigation device determines whether the number of received GPS signals
is smaller than 1.

[0064] If the number of received GPS signals is smaller than 1, the
navigation device determines that no GPS signal is received and goes to
step 211. In step 211, the navigation device estimates the location and
heading of the user, using the PDR algorithm 111 only, without the
satellite navigation algorithm 109.

[0065] If the number of received GPS signals is 1 or larger, the
navigation device compares the strength of a received GPS signal with a
threshold in step 209. If the strength of the received GPS is equal to or
lower than the threshold, the navigation device estimates the location
and heading of the user using the PDR algorithm 111 only in step 211. If
the strength of the received GPS is higher than the threshold, the
navigation device estimates the current location and heading of the
navigation device by tightly coupling the satellite navigation algorithm
with the PDR algorithm 111 in step 213. With the tightly coupled
algorithms, the location error of the user can be corrected even when the
user is located in a poor reception area where 4 or fewer satellite
signals are received.

[0066]FIG. 3 is a flowchart illustrating an error correction operation
according to an exemplary embodiment of the present invention.

[0067] In exemplary embodiments of the present invention, a Kalman filter
may be used. The Kalman filter may be used to obtain an optimum estimate
of a state variable and may be applied to a linear system that has a
linear structure and minimizes the error variance of an estimated state
variable.

[0068] Referring to FIG. 3, the navigation device receives a GPS signal in
step 301. The received GPS signal is transmitted to the Kalman filter. In
step 303, the Kalman filter generates a measurement using the received
GPS signal. Since the GPS signal carries pseudo-range information and
pseudo-range change rate information, the Kalman filter uses the
pseudo-range information and pseudo-range change rate information in
generating the measurement. Then, a state variable measurement is updated
with the generated measurement in step 305. Specifically, a gain of the
Kalman filter is calculated and the state variable measurement is updated
using the gain. An error of the GPS signal is corrected using the updated
state variable measurement in step 307 and the error-corrected GPS signal
is applied to the PDR system in step 309.

[0069] In accordance with an exemplary embodiment of the present
invention, an error of a reference value is expressed as a state variable
of a Kalman filter, and using the Kalman filter an estimated state
variable is fed back as an input to the system. This is called indirect
feedback. That is, the error propagation characteristics of the system
are maintained linearly by use of the indirect feedback Kalman filter.
The step for calculating an estimate at the Kalman filter is divided into
measurement update performed when a measurement is given and time
propagation calculated with passage of time. In exemplary embodiments of
the present invention, an error of the system may be corrected through
feedback of an error state variable estimated by measurement updating to
the system. Thus, the time propagation of the state variable on a system
model is not performed after the feedback. Rather, the state variable of
the Kalman filter is reset to 0 and measurement updating using a
measurement is repeated in the next step.

[0070] The below-described graphs illustrate estimates of a current
location or destination of a user that uses a navigation device in a
composite navigation system that tightly couples the PDR system with the
satellite navigation system. In the case of the tightly coupled scheme, a
location error of the satellite navigation system is corrected using a
Kalman filter.

[0071] FIGS. 4A to 5B are graphs illustrating filter tuning results
obtained by taking into account gait characteristics according to
exemplary embodiments of the present invention.

[0073] It can be noted from FIGS. 4A to 5B that GPS data approximates with
respect to an actual trajectory may be tracked successfully irrespective
of a heading bias error.

[0074] At this point should be noted that the exemplary embodiments of the
present disclosure as described above typically involve the processing of
input data and the generation of output data to some extent. This input
data processing and output data generation may be implemented in hardware
or software in combination with hardware. For example, specific
electronic components may be employed in a mobile device or similar or
related circuitry for implementing the functions associated with the
exemplary embodiments of the present invention as described above.
Alternatively, one or more processors operating in accordance with stored
instructions may implement the functions associated with the exemplary
embodiments of the present invention as described above. If such is the
case, it is within the scope of the present disclosure that such
instructions may be stored on one or more processor readable mediums.
Examples of the processor readable mediums include Read-Only Memory
(ROM), Random-Access Memory (RAM), CD-ROMs, magnetic tapes, floppy disks,
and optical data storage devices. The processor readable mediums can also
be distributed over network coupled computer systems so that the
instructions are stored and executed in a distributed fashion. Also,
functional computer programs, instructions, and instruction segments for
accomplishing the present invention can be easily construed by
programmers skilled in the art to which the present invention pertains.

[0075] While the invention has been shown and described with reference to
certain exemplary embodiments thereof, it will be understood by those
skilled in the art that various changes in form and details may be made
therein without departing from the spirit and scope of the invention as
defined by the following claims and their equivalents.

Patent applications by Chan-Gook Park, Seoul KR

Patent applications by Hyun-Su Hong, Seongnam-Si KR

Patent applications by Kyong-Ha Park, Suwon-Si KR

Patent applications by Seung-Hyuck Shin, Seoul KR

Patent applications by Sung-Min Park, Seoul KR

Patent applications by Samsung Electronics Co.,Ltd.

Patent applications by SEOUL NATIONAL UNIVERSITY R & DB FOUNDATION

Patent applications in class Having a self-contained position computing mechanism (e.g., dead-reckoning, etc.)

Patent applications in all subclasses Having a self-contained position computing mechanism (e.g., dead-reckoning, etc.)